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GETRLIMIT(2)		    BSD	System Calls Manual		  GETRLIMIT(2)

     getrlimit,	setrlimit -- control maximum system resource consumption

     #include <sys/time.h>
     #include <sys/resource.h>

     getrlimit(int resource, struct rlimit *rlp);

     setrlimit(int resource, struct rlimit *rlp);

     Limits on the consumption of system resources by the current process and
     each process it creates may be obtained with the getrlimit() call,	and
     set with the setrlimit() call.

     The resource parameter is one of the following:

     RLIMIT_CPU	     the maximum amount	of cpu time (in	seconds) to be used by
		     each process.

     RLIMIT_FSIZE    the largest size, in bytes, of any	single file that may
		     be	created.

     RLIMIT_DATA     the maximum size, in bytes, of the	data segment for a
		     process; this defines how far a program may extend	its
		     break with	the sbrk(2) system call.

     RLIMIT_STACK    the maximum size, in bytes, of the	stack segment for a
		     process; this defines how far a program's stack segment
		     may be extended.  Stack extension is performed automati-
		     cally by the system.

     RLIMIT_CORE     the largest size, in bytes, of a core file	that may be

     RLIMIT_RSS	     the maximum size, in bytes, to which a process's resident
		     set size may grow.	 This imposes a	limit on the amount of
		     physical memory to	be given to a process; if memory is
		     tight, the	system will prefer to take memory from pro-
		     cesses that are exceeding their declared resident set

     A resource	limit is specified as a	soft limit and a hard limit.  When a
     soft limit	is exceeded a process may receive a signal (for	example, if
     the cpu time or file size is exceeded), but it will be allowed to con-
     tinue execution until it reaches the hard limit (or modifies its resource
     limit).  The rlimit structure is used to specify the hard and soft	limits
     on	a resource,

	   struct rlimit {
		   int	   rlim_cur;	   /* current (soft) limit */
		   int	   rlim_max;	   /* hard limit */

     Only the super-user may raise the maximum limits.	Other users may	only
     alter rlim_cur within the range from 0 to rlim_max	or (irreversibly)
     lower rlim_max.

     An	"infinite" value for a limit is	defined	as RLIM_INFINITY (0x7fffffff).

     Because this information is stored	in the per-process information,	this
     system call must be executed directly by the shell	if it is to affect all
     future processes created by the shell; limit is thus a built-in command
     to	csh(1).

     The system	refuses	to extend the data or stack space when the limits
     would be exceeded in the normal way: a break call fails if	the data space
     limit is reached.	When the stack limit is	reached, the process receives
     a segmentation fault (SIGSEGV); if	this signal is not caught by a handler
     using the signal stack, this signal will kill the process.

     A file I/O	operation that would create a file larger that the process'
     soft limit	will cause the write to	fail and a signal SIGXFSZ to be	gener-
     ated; this	normally terminates the	process, but may be caught.  When the
     soft cpu time limit is exceeded, a	signal SIGXCPU is sent to the offend-
     ing process.

     A 0 return	value indicates	that the call succeeded, changing or returning
     the resource limit.   A return value of -1	indicates that an error	oc-
     curred, and an error code is stored in the	global location	errno.

     Getrlimit() and setrlimit() will fail if:

     [EFAULT]		The address specified for rlp is invalid.

     [EPERM]		The limit specified to setrlimit() would have raised
			the maximum limit value, and the caller	is not the su-

     csh(1), quota(2), sigvec(2), sigstack(2)

     There should be limit and unlimit commands	in sh(1) as well as in csh.

     The getrlimit function call appeared in 4.2BSD.

4th Berkeley Distribution	March 10, 1991	     4th Berkeley Distribution


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